Self-healing glassy hybrids based on imidazole-functionalized silica nanoparticles with zinc complexes using dynamic and reversible cross-linking

Abstract

Self-healing glass materials can potentially overcome the inherent limitations of glass, such as brittleness and difficulties in repairing broken sections while maintaining its critical properties. This paper reports a structural design and synthetic strategy for preparing glassy self-healing hybrids with high silica contents. The developed hybrids exhibited excellent self-healing properties based on dynamic and reversible crosslinking owing to the high density of zinc/imidazole units on the silica surface. First, core–shell silica nanoparticles with small multifunctional imidazole/butyl units (diameter: approximately10 nm) and good processability (homogeneous colloidal dispersions in common organic solvents) were synthesized. Afterwards, imidazole-functionalized silica nanoparticles were fabricated using Zn species to obtain self-healing hybrids with high silica contents (>60 wt%). These nanoparticles served as multifunctional and reversible crosslinking sites that dissipated energy, resulting in excellent mechanical, thermal, and healing characteristics. The obtained zinc/imidazole-based silica hybrids remain solid with high storage elasticity in the temperature range of 25–160 °C and high thermal stability corresponding to a 5 wt% weight loss above 280 °C, which were critical for self-healing glass applications. They also exhibited a moderate Young’s modulus of 330 MPa and a self-healing recovery efficiency of 87%. The findings of this study provide new insights into the roles of reversible interactions (metal/ligand exchange reactions) at particle–particle interfaces and high surface functionalities that serve as non-covalent crosslinking points. The prepared hybrids with high silica contents remain solid over a wide temperature range, which can open new avenues for self-healing glass materials.